Pole piece processing system, method of processing a pole piece, pole piece, battery, electric device

Abstract

The application belongs to the technical field of batteries, and particularly relates to a tab processing system, a tab processing method, a tab, a battery and a power utilization device. The tab processing system comprises a flame heating unit for performing flame heating treatment on the tab. The tab processing method comprises: performing flame heating treatment on the tab, so that the surface layer temperature of the active layer is greater than or equal to the softening temperature or the melting temperature of the binder and less than the lowest temperature among the decomposition temperature, the oxidation temperature and the ignition temperature of the active material. During the flame heating treatment, the binder floating to the surface of the tab can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillary pores of the tab increases, the channel for electrolyte infiltration in the tab is increased, the electrolyte is more easily infiltrated into the tab, and thus the electrolyte wettability of the tab is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to a tab processing system, a tab processing method, a tab, a battery, and a power utilization device. BACKGROUND

[0002] With the development of the new energy industry, the research on batteries is becoming more and more popular, and the market requirements are also increasing. However, there are still many problems to be solved for batteries, such as poor electrolyte wettability of the tab.

[0003] In the case of poor electrolyte wettability of the tab, the tab that is not wetted by the electrolyte is difficult to participate in the electrochemical reaction of the battery, reducing the ions that can be freely conducted between the positive and negative electrodes, thereby affecting the charge and discharge capacity of the battery. At the same time, in the case that the tab cannot participate in the electrochemical reaction of the battery, it will also cause the increase of the battery interface resistance, affecting the rate performance, discharge capacity and cycle performance of the battery. Therefore, the electrolyte wettability of the tab is related to the various electrochemical performances of the battery, such as the charge and discharge capacity, rate performance, cycle performance, etc. Improving the electrolyte wettability of the tab is of great significance to improve the performance of the battery. SUMMARY

[0004] In view of the above problems, the present application provides a tab processing system, a tab processing method, a tab, a battery, and a power utilization device, which can improve the electrolyte wettability of the tab.

[0005] In a first aspect, the present application provides a tab processing system, comprising: a flame heating unit, configured to perform flame heating treatment on the tab.

[0006] The tab processing system of the present application can perform flame heating treatment on the tab by setting the flame heating unit. During the flame heating treatment, the binder floating to the surface of the tab can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillary pores in the tab increases, increasing the channels for electrolyte infiltration in the tab, making it easier for the electrolyte to infiltrate the tab, thereby improving the electrolyte wettability of the tab.

[0007] In addition, the tab processing system of the present application can be integrated into the existing tab production line. Only the flame heating unit needs to be added to the existing tab production line, without the need for additional production line modification time, equipment, and has a good cost advantage.

[0008] In some embodiments, the flame heating unit generates flames located on opposite sides of the surface of the tab. In this way, the opposite two surfaces of the tab can be subjected to flame heating treatment, so that the binder on both surfaces of the tab is softened (melted) or ablated, which is conducive to improving the processing efficiency of the tab.

[0009] In some embodiments, the flame heating unit comprises a flameless gas burner. The embodiments of the present application provide the flameless gas burner in the flame heating unit, which not only facilitates the rapid heating of the pole piece, but also improves the situation that the carbon deposition on the surface of the pole piece leads to the decrease of the surface pore of the pole piece, and helps to improve the overall capillary distribution of the pole piece, and further accelerates the electrolyte infiltration rate of the pole piece.

[0010] In some embodiments, the pole piece processing system further comprises a conveying unit for conveying the pole piece. Under the action of the conveying unit, the pole piece enters the flame heating unit and other processes in an orderly manner, and the continuous and uninterrupted work can be realized. Moreover, by adjusting the running speed of the conveying unit, the rapid heating of the pole piece by the flame generated by the flame heating unit can be realized, and the processing efficiency can be improved.

[0011] In the second aspect, the present application provides a method for processing a pole piece, the pole piece comprising an active layer, the active layer comprising an active substance and a binder; the method for processing the pole piece comprising: performing a flame heating treatment on the pole piece, so that the surface layer temperature of the active layer is greater than or equal to the softening temperature or melting temperature of the binder, and less than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active substance.

[0012] In the method of the embodiments of the present application, the pole piece is processed by using the flame heating mode, and the temperature of the active layer in the flame heating treatment process is controlled, so that the binder floating to the surface of the pole piece is softened (melted) or ablated. After the binder floating to the surface of the pole piece is softened (melted) or ablated, the number of capillary pores in the pole piece increases, the channel for the electrolyte to infiltrate in the pole piece increases, the electrolyte is more easily infiltrated into the pole piece, and the electrolyte infiltration property of the pole piece is improved.

[0013] At the same time, in the flame heating treatment process, the temperature of the active layer is less than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active substance, so that the decomposition, oxidation and combustion of the active substance in the flame heating treatment process are prevented, and the lattice stability of the active substance and the structural stability of the pole piece are maintained.

[0014] In some embodiments, the flame used in the flame heating treatment comprises a premixed combustion flame. The embodiments of the present application use the premixed combustion flame to perform the flame heating treatment on the pole piece, which not only facilitates the rapid heating of the pole piece, but also improves the situation that the carbon deposition on the surface of the pole piece leads to the decrease of the surface pore of the pole piece, and helps to improve the overall capillary distribution of the pole piece, and further accelerates the electrolyte infiltration rate of the pole piece.

[0015] In some embodiments, the temperature of the premixed combustion flame is 500-1200℃, optionally 600-1000℃. The high-temperature flame is used to heat the electrode tab, which can rapidly heat the electrode tab to the required temperature.

[0016] In some embodiments, the premixed combustion flame is generated by a flameless gas burner, which comprises any one or more of the following technical parameters:

[0017] (1) air flow rate 50-250 L / min, optionally 80-150 L / min;

[0018] (2) gas fuel flow rate 2-15 L / min, optionally 5-10 L / min;

[0019] (3) air-fuel ratio 1-7, optionally 3-5.

[0020] The premixed combustion flame is generated by the flameless gas burner in the embodiments of the present application, which can rapidly heat the active layer to the required temperature. Meanwhile, under a certain air flow rate, gas fuel flow rate and air-fuel ratio, the gas fuel can be fully combusted, the flame generated by the combustion has fewer free carbon particles and lower blackness, which can improve the situation that the surface pores of the electrode tab are reduced due to the carbon deposition on the surface of the electrode tab during the flame heating process.

[0021] In some embodiments, the electrode tab moves relative to the flame during the flame heating process. By moving, the residence time of the electrode tab under the flame can be adjusted, which can rapidly and instantaneously heat the electrode tab and is conducive to improving the processing efficiency. Meanwhile, since the flame has a high temperature, by controlling the movement of the electrode tab relative to the flame, the contact time of the flame and the electrode tab can be reduced, and the temperature of the electrode tab can be controlled within a suitable range.

[0022] In some embodiments, the movement speed of the electrode tab relative to the flame is 40-100 m / min, optionally 60-80 m / min. The electrode tab moves relative to the flame at a high speed in the embodiments of the present application, the electrode tab has a short residence time under the flame, which can rapidly and instantaneously heat the electrode tab and control the temperature of the active layer in the electrode tab within a required range during the flame heating process.

[0023] In some embodiments, the active layer surface layer temperature is 180-500℃, optionally 300-500℃. These temperature ranges are greater than or equal to the softening temperature or melting temperature of common electrode tab adhesives, and less than the lowest of the decomposition temperature, oxidation temperature, and ignition temperature of common electrode tab active materials, which can effectively soften (melt) or ablate the adhesive floating on the surface of the electrode tab, while improving the decomposition, oxidation, or combustion of the active material during the flame heating process, maintaining the lattice stability of the active material and the structural stability of the electrode tab.

[0024] In a third aspect, the present application provides an electrode tab, the porosity of the electrode tab is 30%-50%, optionally 30%-47%; the electrode tab is obtained by the method according to the second aspect of the present application.

[0025] After the flame heating treatment, the adhesive floating on the surface of the electrode tab is softened (melted) or ablated, and the electrode tab exposes more capillary pores, so that the treated electrode tab has high porosity, which is beneficial to increase the channel for electrolyte to infiltrate the electrode tab, so that the electrolyte can more easily infiltrate the electrode tab, thereby improving the wettability of the electrolyte to the electrode tab.

[0026] In a fourth aspect, the present application provides a battery, the battery comprising the electrode tab according to the third aspect of the present application.

[0027] The battery according to the embodiments of the present application comprises the above-mentioned electrode tab, which can be a positive electrode tab or a negative electrode tab, or can comprise both a positive electrode tab and a negative electrode tab. Since the adhesive floating in the electrode tab of the battery is softened (melted) or ablated, the electrode tab has higher porosity, which is beneficial to improve the wettability of the electrolyte to the electrode tab, thereby helping to improve the electrochemical performance of the battery.

[0028] In a fifth aspect, the present application provides a power consuming device, the power consuming device comprising the battery according to the fourth aspect of the present application.

[0029] The battery disclosed in the embodiments of the present application can be used in a power consuming device using a battery as a power source, or various energy storage systems using a battery as an energy storage element, for providing electric energy. The power consuming device can include but is not limited to a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. Among them, the electric toy can include a fixed or mobile electric toy, for example, a game console, an electric car toy, an electric ship toy, and an electric plane toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc. As the power consuming device, a battery cell, a battery module, or a battery pack in a secondary battery can be selected according to the use requirement. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0031] Figure 1 The structural schematic diagram of the pole piece processing system provided for the embodiment A1 of the present application;

[0032] Figure 2 The schematic diagram of the battery module of an embodiment of the present application;

[0033] Figure 3 The schematic diagram of the battery pack of an embodiment of the present application;

[0034] Figure 4 The schematic diagram of the battery pack of an embodiment of the present application is shown in FIG. 1. Figure 3 The exploded view of the battery pack of an embodiment of the present application is shown in FIG. 2.

[0035] Figure 5 The schematic diagram of the battery of an embodiment of the present application is shown in FIG. 3.

[0036] Figure 6 The exploded view of the battery of an embodiment of the present application is shown in FIG. 4. Figure 5 The schematic diagram of the battery of an embodiment of the present application is shown in FIG. 3.

[0037] Figure 7 The schematic diagram of the battery used as a power supply for the power consumption device of an embodiment of the present application is shown in FIG. 5.

[0038] Reference signs:

[0039] 10-pole piece; 20-conveying unit; 21-unwinding guide roller; 22-winding guide roller; 30-flame heating unit; D-conveying direction of the pole piece; 1-battery pack; 2-upper box body; 3-lower box body; 4-battery module; 5-battery cell; 51-housing; 52-electrode assembly; 53-cover plate. DETAILED DESCRIPTION

[0040] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a reference to the plural and vice versa.

[0042] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0043] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, or to a particular embodiment, or to a particular set of embodiments. It will be explicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0045] In the description of the embodiments of the present application, the term "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0046] It should be understood that in various embodiments of the present application, the size of the sequence number of the above processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0047] The mass of the related components mentioned in the embodiments of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the masses of each component. Therefore, as long as the content of the related components in the embodiments of the present application is scaled up or down in proportion, it is within the scope disclosed in the embodiments of the present application. Specifically, the mass in the embodiments of the present application can be μg, mg, g, kg, and other mass units commonly known in the chemical industry.

[0048] With the development of the new energy industry, the research on batteries is becoming more and more popular, and the market requirements are also increasing. However, there are still many problems to be solved in batteries, such as poor wettability of the pole piece.

[0049] In the case of poor electrolyte wettability of the pole piece, the pole piece that is not wetted by the electrolyte is difficult to participate in the electrochemical reaction of the battery, reducing the ions that can be freely conducted between the positive and negative electrodes, thereby affecting the charge and discharge capacity of the battery. At the same time, in the case that the pole piece cannot participate in the electrochemical reaction of the battery, it will also cause the increase of the battery interface resistance, affecting the rate performance, discharge capacity and cycle performance of the battery. Therefore, the electrolyte wettability of the pole piece is related to the various electrochemical performances of the battery, such as the charge and discharge capacity, rate performance, cycle performance, etc.

[0050] Through analysis, the electrolyte wettability of the pole piece is affected by various factors in the pole piece processing process. For example, energy density is an important indicator of the battery, the greater the energy density, the more electric energy the battery can release. In order to improve the energy density of the battery, thick coating method can be used to make the pole piece of the battery. That is, during the preparation of the pole piece, the proportion of active material to current collector is increased, that is, the coating amount of the pole piece slurry is increased. However, the increase of the coating amount of the pole piece slurry also leads to the increase of the thickness of the pole piece, which is easy to reduce the electrolyte wettability rate of the pole piece.

[0051] At the same time, the thick coating method of the pole piece leads to the increase of the thickness of the pole piece, which is not consistent with the market demand for the portability and small size of the battery. Therefore, it is often necessary to improve the compaction density of the pole piece as much as possible during the preparation of the pole piece. However, this will make the pores between the active materials in the pole piece become smaller and smaller, and the electrolyte is not easy to wet. Moreover, after the pole piece slurry is coated on the current collector in the preparation process of the pole piece, the solvent in the pole piece slurry is often removed through drying process to form a stable pole piece. During the drying process, the solvent in the pole piece slurry migrates to the surface of the pole piece and evaporates through capillary force, and the commonly used binder has light density and large specific surface area, which is easy to migrate to the surface of the pole piece with the evaporation of the solvent, causing the problem of binder floating. The floating of the binder will block the pores of the pole piece, so that the electrolyte cannot be immersed in the fine pores of the pole piece, thereby reducing the electrolyte wettability rate of the pole piece and affecting the various electrochemical performances of the battery.

[0052] In order to improve the wettability of the electrolyte to the electrode sheet, the embodiment of the present application sets a flame heating unit capable of generating flame in the electrode sheet processing system, which is used for flame heating treatment of the electrode sheet. Alternatively, in the processing method of the electrode sheet, a process of flame heating treatment of the electrode sheet is set. During the flame heating treatment, the binder floating to the surface of the electrode sheet can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, more capillary pores of the electrode sheet are exposed, the channel for the electrolyte to infiltrate the electrode sheet is increased, the electrolyte is more easily infiltrated into the electrode sheet, and thus the electrolyte wettability of the electrode sheet is improved. At the same time, the method of the embodiment of the present application has the advantages of obvious effect and low cost.

[0053] The electrode sheet heating system or the electrode sheet processing method disclosed by the embodiment of the present application can be used to manufacture positive electrode sheets or negative electrode sheets with excellent performance, and has wide applicability. Moreover, the manufactured electrode sheet can be applied to a battery and an electric device using the battery as a power supply, which can be but is not limited to a mobile phone, a tablet computer, a notebook computer, an electric toy, an electric tool, an electric vehicle, a ship, a spacecraft, etc. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, an electric plane toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc.

[0054] The present application will be further described in conjunction with the embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0055] The first aspect of the embodiment of the present application provides an electrode sheet processing system, comprising: a flame heating unit, the flame heating unit is used for flame heating treatment of the electrode sheet.

[0056] The electrode sheet processing system refers to a process equipment for manufacturing and processing the electrode sheet. Flame heating is a way of using flame to burn the sample to increase the temperature of the sample.

[0057] The electrode sheet processing system of the embodiment of the present application sets a flame heating unit to perform flame heating treatment on the electrode sheet. During the flame heating treatment, the binder floating to the surface of the electrode sheet can be softened (melted) or ablated. After the floating binder is softened (melted) or ablated, the number of capillary pores in the electrode sheet is increased, the channel for the electrolyte to infiltrate the electrode sheet is increased, the electrolyte is more easily infiltrated into the electrode sheet, and thus the electrolyte wettability of the electrode sheet is improved.

[0058] In addition, the electrode sheet processing system of the embodiment of the present application can be integrated into the existing electrode sheet production line. Only the flame heating unit needs to be added to the existing electrode sheet production line, without the need to additionally increase a large amount of production line modification time and equipment, which has a good cost advantage.

[0059] In some embodiments, the flame heating unit generates flames located on opposite sides of the surface of the pole piece. In this way, both opposite surfaces of the pole piece can be subjected to the flame heating treatment, so that the adhesives on both surfaces of the pole piece are softened (melted) or ablated, which is conducive to improving the processing efficiency of the pole piece.

[0060] In some embodiments, the flame heating unit comprises a flameless gas burner.

[0061] A gas burner is a device that converts gas fuel into heat energy through combustion. According to the difference of the combustion flame, the gas burner can be divided into a flame gas burner and a flameless gas burner. Among them, the flame formed by the burner in the flame gas burner has strong light radiation, and its working principle is gas diffusion combustion. The flameless gas burner has weak light radiation, and its working principle is gas premixed combustion (there is part of diffusion combustion in the actual flameless gas burner, that is, the working principle belongs to local premixed combustion).

[0062] Among them, gas diffusion combustion and gas premixed combustion are two different combustion modes of gas. In gas diffusion combustion, the gas fuel and the oxidant (air or oxygen) are not in contact before ignition and are sent into the combustion chamber for combustion. Exemplarily, the combustion of torches, kerosene lamps, alcohol lamps and the like belongs to gas diffusion combustion. Gas diffusion combustion has the disadvantages of poor combustion stability and low heat release rate, and because the gas fuel and the oxidant are not in contact before ignition, the combustion is incomplete and carbon particles are generated, which can easily form carbon deposition on the surface of the sample subjected to the flame heating treatment.

[0063] Gas premixed combustion is the combustion of gas fuel and oxidant after they have been mixed and contacted before ignition. Gas premixed combustion has the advantages of high thermal intensity and high combustion temperature, and by controlling the content of the oxidant in the premixing, the gas fuel can be completely combusted, reducing the carbon soot generated during combustion. In addition, gas premixed combustion also has the characteristic of fast combustion speed, and the carbon hydrogen compounds in the gas fuel do not have time to decompose, so that there are fewer free carbon particles in the flame, and the darkness of the flame is lower.

[0064] Therefore, the flameless gas burner is arranged in the flame heating unit in the embodiments of the present application, which is not only conducive to rapid heating of the pole piece, but also can improve the situation that the surface pores of the pole piece are reduced due to carbon deposition on the surface of the pole piece during the flame heating treatment, and is helpful to improve the overall capillary pore distribution of the pole piece, and further speed up the electrolyte infiltration rate of the pole piece.

[0065] Exemplarily, the flameless gas burner of the embodiments of the present application comprises a jet gas burner, i.e. a lance burner.

[0066] In some embodiments, the gas fuel used by the flameless gas burner includes one or more of natural gas, hydrogen, carbon monoxide, methane, ethane, ethylene, propylene, acetylene, and propyne. These gas fuels have the advantages of high heat intensity and high combustion temperature in the combustion process, and can achieve rapid flame heating of the pole piece.

[0067] In some embodiments, the pole piece processing system further includes a conveying unit for conveying the pole piece.

[0068] Under the action of the conveying unit, the pole piece enters the flame heating unit and other processes in an orderly manner for processing, and the system can work continuously and uninterruptedly. The conveying unit can include a pay-off guide roller and a winding guide roller arranged in sequence, respectively used for unwinding and winding the pole piece. By placing the pole piece on the pay-off guide roller and the winding guide roller and operating the winding guide roller, the pole piece can be moved relative to the flame heating unit under the traction of the winding guide roller. The running speed of the winding guide roller can be set to 40-100 m / min, optionally 60-80 m / min, including but not limited to any one of 40 m / min, 45 m / min, 50 m / min, 55 m / min, 60 m / min, 65 m / min, 70 m / min, 75 m / min, 80 m / min, 85 m / min, 90 m / min, 95 m / min, 100 m / min, or a range value between any two of them, or set to other running speeds according to actual needs. By adjusting the running speed of the conveying unit, the pole piece can quickly pass through the flame generated by the flame heating unit, achieving rapid heating of the pole piece and improving the processing efficiency.

[0069] In some embodiments, the pole piece processing system further includes a temperature measuring unit for measuring the temperature of the pole piece. By setting the temperature measuring unit, the temperature of the pole piece can be timely and accurately understood, and the state of the pole piece can be monitored. The temperature measuring unit can be used to measure the surface temperature of the pole piece, the internal temperature of the pole piece, or both the surface temperature and the internal temperature of the pole piece. Meanwhile, the temperature measuring unit can be used to measure the temperature of the pole piece being subjected to flame heating processing, or the temperature of the pole piece after the flame heating processing, for example, the temperature of the pole piece 3-10 cm (such as 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm) downstream of the flame heating.

[0070] In some embodiments, the temperature measuring unit includes an infrared temperature measuring module. By means of infrared temperature measurement, non-contact temperature measurement of the pole piece can be achieved.

[0071] In some embodiments, the pole piece processing system further comprises an automatic temperature control unit configured to control the heating condition of the flame heating unit, for example, to control the flow of gas fuel, the flow of air, etc. in the flame heating unit. The automatic temperature control unit can receive the temperature data of the pole piece measured by the temperature measuring unit, and control the flame heating unit according to the temperature data, so as to accurately and effectively soften (melt) or ablate the binder floating on the pole piece, and reduce the adverse effects on other components of the pole piece.

[0072] In some embodiments, the pole piece processing system further comprises a drying unit configured to perform drying treatment on the pole piece coated with the electrode slurry, and the drying unit and the flame heating unit are arranged in sequence along the conveying direction of the pole piece. The pole piece coated with the electrode slurry refers to the pole piece formed by coating the electrode slurry on the current collector (usually on one surface or both surfaces of the current collector), and at this time, the electrode slurry has not been dried and still contains solvent. The drying unit and the flame heating unit are arranged in sequence along the conveying direction of the pole piece, which means that the pole piece passes through the drying unit first and then passes through the flame heating unit. After the drying treatment of the drying unit, the binder in the electrode slurry appears to float to the surface of the pole piece, affecting the structure of the pole piece. Therefore, after the treatment of the flame heating unit, the floating binder can be softened (melted) or ablated.

[0073] In some embodiments, the pole piece processing system further comprises a rolling unit configured to perform rolling treatment on the pole piece, and the rolling unit and the flame heating unit are arranged in sequence along the conveying direction of the pole piece, or the drying unit, the rolling unit and the flame heating unit are arranged in sequence along the conveying direction of the pole piece. The rolling mode usually includes cold pressing, hot pressing, etc. After rolling, the adhesion of the pole piece can be enhanced, and the pole piece can have a desired compactness.

[0074] In some embodiments, the pole piece processing system further comprises a cooling unit configured to perform cooling treatment on the pole piece, and the flame heating unit and the cooling unit are arranged in sequence along the conveying direction of the pole piece. After the treatment of the pole piece by the flame heating unit, the pole piece usually needs to be wound up, and a high temperature of the pole piece is not conducive to winding. Therefore, the cooling treatment of the pole piece by the cooling unit can reduce the temperature of the pole piece, which is helpful for the subsequent winding of the pole piece.

[0075] The second aspect of the embodiments of the present application provides a method for processing a pole piece, the pole piece comprising an active layer, the active layer comprising an active substance and a binder, and the method for processing the pole piece comprises: performing flame heating treatment on the pole piece, so that the surface layer temperature of the active layer is greater than or equal to the softening temperature or melting temperature of the binder, and less than the lowest temperature among the decomposition temperature, the oxidation temperature and the ignition temperature of the active substance.

[0076] The active material is a material in the electrode plate that participates in the electrochemical reaction of the battery and can serve as a medium for the transfer of ions in the electrochemical reaction. The binder is a high molecular compound used to bind the various components in the active layer (e.g., the active material and other materials) and the current collector to each other, mainly serving to bind and maintain the firmness of the active material in the active layer and to enhance the binding strength between the active layer and the current collector. The binder is mixed with the active material, solvent, and other necessary components to form a slurry, which is coated on at least one side of the current collector. After the solvent evaporates, the slurry dries to form the active layer of the electrode plate.

[0077] In the embodiments of the present application, the surface layer of the active layer refers to the outermost layer of the active layer that is in contact with the outside world. Generally, the electrode plate includes a current collector and an active layer disposed on at least one side of the current collector, so the surface layer of the active layer is usually also the surface layer of the electrode plate. Generally, the region within 40% of the thickness of the electrode plate along the thickness direction of the electrode plate and from the outside to the inside can be considered as the surface layer of the electrode plate. For example, for an electrode plate with a commonly used thickness of 50-300 μm, the region with a thickness of 0-20 μm (along the thickness direction of the electrode plate and from the outside to the inside) can be considered as the surface layer of the electrode plate, that is, the surface layer of the active layer. In the active layer, the region outside the surface layer of the active layer can be considered as the interior of the active layer. During the flame heating process, the temperature of the surface layer of the active layer can be the temperature of the region of the surface layer of the active layer that is being heated by the flame, or the temperature of the region downstream of the surface layer of the active layer under the flame heating, for example, the temperature of the region 3-10 cm (such as any one of 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, or a range value between any two of them) downstream of the flame heating, which is close to the region heated by the flame, and its temperature can generally be considered the same as the temperature of the surface layer of the active layer during the flame heating process.

[0078] The softening temperature is the temperature at which the three-dimensional long-range ordered state of the molecular chain structure of the non-crystalline polymer is converted into the disordered viscous flow state. The melting temperature is the temperature at which the three-dimensional long-range ordered state of the molecular chain structure of the crystalline polymer is converted into the disordered viscous flow state, also known as the melting point, which is the lower limit of the forming and processing temperature of the crystalline polymer. Generally, the melting temperature interval is relatively narrow, while the softening temperature interval is relatively wide.

[0079] The decomposition temperature of the active material refers to the temperature at which the molecular structure of the active material is destroyed or the crystal lattice is distorted, although no combustion reaction occurs. The oxidation temperature of the active material is the minimum temperature required for the active material to undergo oxidation. The ignition temperature of the active material, also known as the ignition temperature, is the minimum temperature at which the active material undergoes combustion.

[0080] In the method of the embodiments of the present application, the binder floating to the surface of the pole piece is softened (melted) or ablated by treating the pole piece by flame heating and controlling the surface layer temperature of the active layer during the flame heating treatment. After the floating binder is softened (melted) or ablated, the number of capillary pores in the pole piece increases, increasing the channels for electrolyte infiltration in the pole piece, making it easier for the electrolyte to infiltrate the pole piece, thereby improving the electrolyte wettability of the pole piece.

[0081] At the same time, during the flame heating treatment, the surface layer temperature of the active layer is less than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active material, which can reduce the decomposition, oxidation and combustion of the active material during the flame heating treatment, and maintain the lattice stability of the active material and the structural stability of the pole piece.

[0082] In some embodiments, the solvent mass concentration in the active layer described above is as low as ppm level, such as less than 1000 ppm. The active layer with such a low concentration is a dried active layer, and there is floating binder on the surface thereof. The embodiments of the present application perform flame heating treatment on the pole piece with the dried active layer, which can treat the floating binder and improve the performance of the pole piece.

[0083] In some embodiments, the flame used for the flame heating treatment includes a premixed combustion flame.

[0084] Premixed combustion, also known as gas premixed combustion, is a combustion mode of gas fuel, and the premixed combustion flame is a flame generated by using this combustion mode. Gas premixed combustion is a combustion that occurs after gas premixing, in which the gas fuel and the oxidizer are mixed and contacted before ignition. Gas premixed combustion has the advantages of high thermal intensity and high combustion temperature, and by controlling the content of the oxidizer in premixing, the gas fuel can be completely combusted, reducing the soot generated during combustion. In addition, gas premixed combustion has the characteristic of fast combustion speed, and the hydrocarbons in the gas fuel do not have time to decompose, resulting in fewer free carbon particles in the flame and lower blackness of the flame. Therefore, by using a premixed combustion flame to perform flame heating treatment on the pole piece, the embodiments of the present application not only facilitate rapid heating of the pole piece, but also can improve the situation that the carbon deposition on the surface of the pole piece during the flame heating treatment reduces the surface porosity of the pole piece, which helps to improve the overall capillary pore distribution of the pole piece and further accelerate the electrolyte infiltration rate of the pole piece.

[0085] In some embodiments, the temperature of the premixed combustion flame is 500-1200°C, optionally 600-1000°C, including but not limited to any one of 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C or a range value between any two of them. The premixed combustion flame is uniform and has no obvious stratification, so the temperature of the premixed combustion flame refers to the temperature of any region of the entire flame. The temperature of the premixed combustion flame can be obtained by contact measurement using a thermocouple, light, etc., or non-contact measurement using imaging, laser spectroscopy, radiation, etc. Flame heating treatment of the pole piece using a high-temperature flame can quickly heat the pole piece to the desired temperature.

[0086] In some embodiments, the premixed combustion flame is generated by a flameless gas burner, which includes any one or more of the following technical parameters:

[0087] (1) Air flow rate: 50-250 L / min, optionally 80-150 L / min;

[0088] (2) Gas fuel flow rate: 2-15 L / min, optionally 5-10 L / min;

[0089] (3) Air-fuel ratio: 1-7, optionally 3-5.

[0090] Wherein, the air flow rate includes but is not limited to any one of 50 L / min, 60 L / min, 70 L / min, 80 L / min, 90 L / min, 100 L / min, 110 L / min, 120 L / min, 130 L / min, 140 L / min, 150 L / min, 160 L / min, 170 L / min, 180 L / min, 190 L / min, 200 L / min, 210 L / min, 220 L / min, 230 L / min, 240 L / min, 250 L / min or a range value between any two of them.

[0091] The gas fuel flow rate includes but is not limited to any one of 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min, 15 L / min or a range value between any two of them.

[0092] Air-fuel ratio refers to the mass ratio between air and gaseous fuel in the mixture formed by premixing air and gaseous fuel. The air-fuel ratio includes but is not limited to any one of 1, 2, 3, 4, 5, 6, 7 or a range value between any two of them.

[0093] The embodiment of the present application adopts a flameless gas burner to generate a premixed combustion flame, which can quickly heat the active layer to the required temperature. At the same time, under a certain air flow, gaseous fuel flow and air-fuel ratio, the gaseous fuel can be fully combusted, and the flame produced by the combustion has fewer free carbon particles and lower blackness, which can improve the situation that the deposition of carbon on the surface of the pole piece reduces the surface porosity of the pole piece during the flame heating treatment process.

[0094] In some embodiments, the pole piece moves relative to the flame during the flame heating treatment step. By moving, the residence time of the pole piece under the flame can be adjusted to achieve rapid and instantaneous heating of the pole piece and improve the processing efficiency. At the same time, since the flame has a high temperature, by controlling the movement of the pole piece relative to the flame, the contact time between the flame and the pole piece can be reduced, and the temperature of the pole piece can be controlled within a suitable range.

[0095] In some embodiments, the moving speed of the pole piece relative to the flame is 40-100 m / min, and can be 60-80 m / min, including but not limited to any one of 40 m / min, 45 m / min, 50 m / min, 55 m / min, 60 m / min, 65 m / min, 70 m / min, 75 m / min, 80 m / min, 85 m / min, 90 m / min, 95 m / min, 100 m / min or a range value between any two of them. The pole piece of the embodiment of the present application moves quickly relative to the flame, and the pole piece has a short residence time under the flame, which realizes rapid and instantaneous heating of the pole piece and controls the temperature of the active layer in the pole piece within a required range during the flame heating treatment process. In actual operation, the pole piece can be placed on the unwinding guide roller and the winding guide roller, and the winding guide roller is used to pull the pole piece, so as to realize the movement of the pole piece relative to the flame. By controlling the running speed of the unwinding guide roller and the winding guide roller, the moving speed of the pole piece relative to the flame can be adjusted.

[0096] In some embodiments, the surface temperature of the active layer during the flame heating treatment is in the range of 180-500°C, optionally in the range of 300-500°C, including but not limited to any one of the point values of 180°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C or any range between any two of the point values. The surface temperature of the active layer can be measured by an infrared temperature module or other temperature testing instrument. These temperature ranges are greater than or equal to the softening temperature or melting temperature of common electrode tab adhesives, and less than the lowest of the decomposition temperature, oxidation temperature, and ignition temperature of common electrode tab active materials, which can effectively soften (melt) or ablate the adhesive that floats to the surface in the electrode tab, while improving the decomposition, oxidation, or combustion of the active material during the flame heating treatment, maintaining the lattice stability of the active material and the structural stability of the electrode tab.

[0097] In some embodiments, the porosity of the electrode tab before the flame heating treatment is in the range of 25-32%, including but not limited to any one of the point values of 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or any range between any two of the point values. Generally, the positive electrode tab and the negative electrode tab have different porosities due to the different densities, particle sizes, and types of adhesives used for the active materials, or other factors. For the positive electrode tab, the porosity before the flame heating treatment can be in the range of 30-32%, including but not limited to any one of the point values of 30%, 31%, 32% or any range between any two of the point values. For the negative electrode tab, the porosity before the flame heating treatment can be in the range of 25-28%, including but not limited to any one of the point values of 25%, 26%, 27%, 28% or any range between any two of the point values. The porosity of the electrode tab can be calculated using the apparent volume and the true volume of the electrode tab, i.e., porosity = (V0-V) / V*100%, where V0 is the apparent volume of the electrode tab and V is the true volume of the electrode tab. The method of the present application is suitable for treating electrode tabs with different porosities, and the flame heating treatment can increase the porosity of the electrode tab, thereby improving the electrolyte wettability of the electrode tab.

[0098] In some embodiments, the sheet resistance of the electrode tab before the flame heating treatment is 0.001-0.5 Ω, including but not limited to any one of 0.001 Ω, 0.002 Ω, 0.005 Ω, 0.01 Ω, 0.05 Ω, 0.1 Ω, 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω or a range value between any two of them. Generally, the positive electrode tab and the negative electrode tab have different sheet resistances. For the positive electrode tab, the sheet resistance before the flame heating treatment is generally 0.001-0.01 Ω, including but not limited to any one of 0.001 Ω, 0.002 Ω, 0.005 Ω, 0.01 Ω or a range value between any two of them. For the negative electrode tab, the sheet resistance before the flame heating treatment is generally 0.1-0.5 Ω, including but not limited to any one of 0.1 Ω, 0.2 Ω, 0.3 Ω, 0.4 Ω, 0.5 Ω or a range value between any two of them. The sheet resistance of the electrode tab can be directly tested by a sheet resistance meter. The method of the present application is suitable for treating electrode tabs with different sheet resistances, and the structure of the electrode tab can be improved after the flame heating treatment, for example, the porosity of the electrode tab is increased, which is beneficial to reducing the sheet resistance of the electrode tab.

[0099] In some embodiments, the adhesion of the electrode tab before the flame heating treatment is 18-23 N / m, including but not limited to any one of 18 N / m, 19 N / m, 20 N / m, 21 N / m, 22 N / m, 23 N / m or a range value between any two of them. Generally, the positive electrode tab and the negative electrode tab have different adhesion due to the different types of adhesives used or other factors. For the positive electrode tab, the adhesion before the flame heating treatment can be 18-20 N / m, including but not limited to any one of 18 N / m, 19 N / m, 20 N / m or a range value between any two of them. For the negative electrode tab, the adhesion before the flame heating treatment can be 20-23 N / m, including but not limited to any one of 20 N / m, 21 N / m, 22 N / m, 23 N / m or a range value between any two of them. The adhesion of the electrode tab reflects the bonding strength between the active material, the binder, the conductive agent, the current collector and other components in the electrode tab. The adhesion of the electrode tab can be tested by stretching the electrode tab on the surface of a substrate using a tensile testing machine, recording the displacement and force during the process of peeling off the electrode tab from the substrate, and obtaining the force at which the force is balanced, which is generally considered as the adhesion of the electrode tab. The method of the present application is suitable for treating electrode tabs with different adhesion, and the adhesion of the electrode tab is improved or remains at a comparable level after the flame heating treatment. That is, the electrode tab after the flame heating treatment still has good adhesion and can meet the requirements.

[0100] In some embodiments, the binder includes one or more of an oil-soluble binder, a water-soluble binder, an emulsion-type binder. The oil-soluble binder includes, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polyimide (PI), polytetrafluoroethylene (PTFE), polybutyl acrylate (PBA), polyacrylonitrile (PAN). The water-soluble binder includes, but is not limited to, one or more of carboxymethyl cellulose (CMC), carboxymethyl cellulose salt, polyacrylic acid (PAA), polyacrylic acid salt, polyvinyl alcohol (PVA), sodium alginate (SA), cyclodextrin (CD). The emulsion-type binder includes, but is not limited to, one or more of styrene butadiene rubber (SBR), vinyl acetate resin, acrylic resin (EVA), chlorinated rubber (CR). Depending on the type of active substance in the pole piece, different binders can be selected, and the temperature in the flame heating is determined according to the softening temperature or melting temperature of the binder.

[0101] In some embodiments, the mass content of the binder in the active layer includes, but is not limited to, 0.5% to 10%, optionally 1% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range value between any two of them, and can also be set to other contents as needed.

[0102] In some embodiments, the pole piece includes any one or both of a positive pole piece and a negative pole piece. Whether it is a positive pole piece or a negative pole piece, there is a phenomenon that the binder floats up during the drying process, and the method of the embodiments of the present application is applicable to both positive pole pieces and negative pole pieces.

[0103] In some embodiments, the pole piece is a positive pole piece, and the active substance includes one or more of a metal inorganic active material and an organic active material. The metal inorganic active material includes, but is not limited to, one or more of lithium iron phosphate, lithium manganese phosphate, lithium cobaltate, lithium manganate, lithium nickel cobalt manganate (nickel cobalt manganese ternary material), lithium nickel cobalt aluminum (nickel cobalt aluminum ternary material). The organic active material includes, but is not limited to, one or more of a quinone compound, a carboxylate compound, an acid anhydride compound, and an amide compound.

[0104] In some embodiments, the electrode tab is a negative electrode tab, and the active material includes one or more of carbon-based active material, titanium-based active material, silicon-based active material, nitride, and lithium metal. The carbon-based material includes one or more of graphite (natural graphite, artificial graphite), hard carbon, soft carbon, mesocarbon microbeads, graphene, but is not limited to. The titanium-based active material includes one or more of lithium titanate and titanium dioxide, but is not limited to. The silicon-based active material includes one or more of silicon and silicon dioxide, but is not limited to. The nitride includes lithium nitride, but is not limited to.

[0105] In some embodiments, the mass content of the active material in the active layer includes, but is not limited to, 90% to 98%, optionally 95% to 98%, for example, any one of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or a range value between any two of them, and can also be set to other contents as needed.

[0106] In some embodiments, the active layer further includes a conductive agent. The conductive agent is used to collect micro-currents between the active materials and between the active materials and the current collector, thereby improving the electronic conductivity. At the same time, the conductive agent can also promote the infiltration of the electrolyte to the electrode tab.

[0107] In some embodiments, the conductive agent includes one or more of acetylene black (SP), carbon nanotubes, conductive carbon black (super-P), Ketjen black, carbon fibers, and graphene.

[0108] In some embodiments, the mass content of the conductive agent in the active layer includes, but is not limited to, 0.5% to 10%, optionally 1% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range value between any two of them, and can also be set to other contents as needed.

[0109] In some embodiments, the active layer optionally further includes a thickening agent, such as carboxymethyl cellulose (CMC). The mass content of the thickening agent in the active layer includes, but is not limited to, 0.5% to 5%, optionally 1% to 5%, for example, any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range value between any two of them, and can also be set to other contents as needed.

[0110] In some embodiments, the pole piece further comprises a current collector, and the active layer is disposed on at least one side of the current collector. The current collector on the pole piece serves as a substrate for the active layer to adhere to and transports electrons in the battery chemical reaction. The current collector includes, but is not limited to, a metal current collector, a carbon current collector, a conductive resin current collector, a composite current collector of metal and resin, and the like, and more specifically, for example, copper, aluminum, nickel, titanium, iron, and their respective alloys, stainless steel, carbon fiber, carbon nanotubes (CNT), graphite, and the like.

[0111] In some embodiments, before the flame heating treatment step, any one or both of the following steps is included: a drying treatment step, a rolling treatment step.

[0112] In the manufacturing process of the pole piece, the active material is generally mixed with a binder, a conductive agent, a solvent, and other necessary components to form a slurry. The slurry is coated on the current collector and dried to form the active layer. During the drying process, the solvent volatilizes, and the binder also migrates to the surface of the active layer, causing the binder to float up, which in turn leads to various problems that are not conducive to the electrochemical performance of the pole piece.

[0113] Generally, after the drying treatment, a rolling treatment step is also included. The rolling method generally includes cold pressing, hot pressing, etc. After rolling, the internal adhesion of the pole piece can be enhanced, and the pole piece can have the desired compacted density. The rolling treatment step can be arranged after the drying treatment step and before the flame heating treatment step.

[0114] The method of the embodiments of the present application performs a flame heating treatment on the pole piece after the drying treatment and / or the rolling treatment, which can solve the problem of binder floating up during the drying process and improve the electrolyte wetting performance of the pole piece.

[0115] In some embodiments, after the flame heating treatment step, a cooling treatment step is included. The cooling treatment method includes, but is not limited to, air cooling, circulating water cooling. By cooling the pole piece, the temperature of the pole piece can be reduced, which is helpful for the subsequent processing of the pole piece, such as winding the pole piece.

[0116] The third aspect of the embodiments of the present application provides a pole piece, the porosity of which is 30% to 50%, and optionally 30% to 47%; the pole piece is processed according to the method of the second aspect described above.

[0117] Due to the differences in material types and contents between the positive pole piece and the negative pole piece, as well as other factors, the positive pole piece and the negative pole piece have different porosities after the flame heating treatment. Specifically, the pole piece is a positive pole piece, and the porosity of the positive pole piece is 35% to 50%, including but not limited to any one of 35%, 36%, 37%, 38%, 39%, 40%, 42%, 44%, 46%, 48%, 50%, or a range value between any two of them.

[0118] Alternatively, the electrode tab is a negative electrode tab, and the porosity of the negative electrode tab is 30% to 35%, including but not limited to any one of 30%, 31%, 32%, 33%, 34%, 35% or a range between any two of them.

[0119] After the flame heating treatment, the binder floating on the surface of the electrode tab is softened (melted) or ablated, and the electrode tab exposes more capillaries, so that the treated electrode tab has high porosity, which is conducive to increasing the channels for electrolyte to infiltrate in the electrode tab, making it easier for the electrolyte to infiltrate the electrode tab, thereby improving the electrolyte wettability of the electrode tab.

[0120] In some embodiments, the porosity of the electrode tab of the embodiments of the present application is increased by 14% or more, for example, 14% to 50%, including but not limited to any one of 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% or a range between any two of them. Corresponding to the porosity, the porosity change rate of the positive electrode tab and the negative electrode tab after the flame heating treatment is also different. For the positive electrode tab, the porosity is increased by 19% to 50%, optionally 40% to 50%, including but not limited to any one of 19%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50% or a range between any two of them. For the negative electrode tab, the porosity is increased by 14% to 26%, optionally 22% to 26%, including but not limited to any one of 14%, 16%, 18%, 20%, 22%, 24%, 26% or a range between any two of them.

[0121] In some embodiments, the electrode sheet of the embodiments of the present application has an electrolyte absorption rate that is increased by 18% or more, optionally 18% to 100%, including but not limited to any one of 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% or a range between any two of them, compared to that before the flame heating treatment. The change rate of the electrolyte absorption rate of the positive electrode sheet and the negative electrode sheet is different due to the different porosities. For the positive electrode sheet, the electrolyte absorption rate is increased by 34% to 100%, optionally 78% to 100%, including but not limited to any one of 34%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 78%, 80%, 85%, 90%, 95%, 100% or a range between any two of them, compared to that before the flame heating treatment. For the negative electrode sheet, the electrolyte absorption rate is increased by 18% to 40%, optionally 34% to 40%, including but not limited to any one of 18%, 20%, 25%, 30%, 35%, 40% or a range between any two of them, compared to that before the flame heating treatment. The electrode sheet of the embodiments of the present application has high porosity, so that it has a very fast absorption speed for electrolyte.

[0122] In some embodiments, the electrode sheet of the embodiments of the present application has a sheet resistance that is reduced by 8% or more, optionally 8% to 30%, including but not limited to any one of 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30% or a range between any two of them, compared to that before the flame heating treatment. The change rate of the sheet resistance of different electrode sheets is also different. For the positive electrode sheet, the sheet resistance is reduced by 16% to 30%, optionally 25% to 30%, including but not limited to any one of 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30% or a range between any two of them, compared to that before the flame heating treatment. For the negative electrode sheet, the sheet resistance is reduced by 8% to 15%, optionally 12% to 15%, including but not limited to any one of 8%, 10%, 12%, 14%, 15% or a range between any two of them, compared to that before the flame heating treatment. The sheet resistance of the electrode sheet is improved after the flame heating treatment.

[0123] The fourth aspect of the embodiments of the present application provides a battery, which comprises the electrode sheet of the third aspect described above.

[0124] The battery of the embodiments of the present application includes the above-mentioned electrode tab, which can be a positive electrode tab or a negative electrode tab, or both. Since the binder floating on the electrode tab is softened (melted) and ablated, the electrode tab has a higher porosity, which is beneficial to improving the wettability of the electrolyte to the electrode tab, thereby helping to improve the electrochemical performance of the battery.

[0125] In some embodiments, the battery of the embodiments of the present application includes one or more of primary batteries and secondary batteries. Batteries can be classified into primary batteries and secondary batteries according to whether they can be recharged for reuse. The primary battery cannot be recharged to restore its activity after discharge, while the secondary battery can be recharged to activate the active material to continue to be used after the battery is discharged. The electrode tab of the embodiments of the present application can be applied to both primary batteries and secondary batteries, and has a wide range of applications.

[0126] In some embodiments, the battery of the embodiments of the present application includes one or more of battery monomers, battery modules, and battery packs. In the case of a secondary battery, secondary batteries are classified into battery monomers, battery modules, and battery packs according to different packaging forms. The battery monomer is the most basic unit of the secondary battery, which includes an electrode assembly and an electrolyte. The electrode assembly usually includes a positive electrode tab, a negative electrode tab, and a separator. The battery monomer mainly works by moving metal ions in the electrolyte between the positive electrode tab and the negative electrode tab. In some battery packaging technologies, one or more battery monomers can be integrated into a battery module, and then one or more battery modules can be installed in the box of the battery to form a battery pack. In other battery packaging technologies, one or more battery monomers can be directly installed in the box to form a battery pack, eliminating the intermediate state of the battery module, thereby reducing the mass of the battery pack and improving the energy density of the battery.

[0127] In some embodiments, the battery further includes an electrolyte. The electrolyte can serve as a carrier for ion transmission in the battery.

[0128] In some embodiments, the electrolyte can be an electrolyte solution, which can include a solvent and a lithium salt dissolved in the solvent. The electrolyte can also contain a solid electrolyte, such as a polymer electrolyte, an inorganic solid-state electrolyte, etc., but is not limited thereto.

[0129] The solvent in the electrolyte solution can include a non-aqueous organic solvent, for example, including one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), and ethyl butyrate (EB).

[0130] The lithium salt can include one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoroarsenate), LiFSI (lithium bisfluorosulfonylimide), LiTFSI (lithium bis-trifluoromethanesulfonylimide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluoro(oxalato)borate), LiBOB (lithium bis(oxalato)borate), LiPO2F2 (lithium difluorophosphate), LiDFOP (lithium difluoro(oxalato)phosphate), and LiTFOP (lithium tetrafluoro(oxalato)phosphate), for example, including one or more of LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiBOB (lithium bis(oxalato)borate), LiDFOB (lithium difluoro(oxalato)borate), LiTFSI (lithium bis-trifluoromethanesulfonylimide), and LiFSI (lithium bisfluorosulfonylimide).

[0131] The electrolyte solution can also optionally contain other additives, for example, one or more of vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), succinonitrile (SN), adiponitrile (ADN), glutaronitrile (GLN), hexanetritrile (HTN), 1,3-propane sultone (1,3-PS), vinyl sulfate (DTD), methyl methylsulfate (MMDS), 1-propene-1,3-sultone (PST), 4-methyl ethylene sulfate (PCS), 4-ethyl ethylene sulfate (PES), 4-propyl ethylene sulfate (PEGLST), propylene sulfate (TS), 1,4-butane sultone (1,4-BS), ethylene sulfite (DTO), dimethyl sulfite (DMS), diethyl sulfite (DES), sulfonate cyclic quaternary ammonium salt, tris(trimethylsilyl)phosphate (TMSP), and tris(trimethylsilyl)borate (TMSB), but is not limited thereto.

[0132] In some embodiments, the battery further comprises a separator interposed between the positive electrode sheet and the negative electrode sheet. In some batteries, a separator is needed to separate the positive electrode sheet and the negative electrode sheet, so that the electrons in the battery cannot pass freely, preventing the two poles from short-circuiting, while allowing the ions in the electrolyte to pass freely between the positive and negative electrodes.

[0133] The separator can be any known porous structure separator film with electrochemical stability and mechanical stability, such as glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF) single or multi-layer film.

[0134] The positive electrode sheet and the negative electrode sheet are alternately stacked, and a separator is interposed between the positive electrode sheet and the negative electrode sheet to play a role of separation, to obtain a bare cell, which can also be obtained after winding. The cell is placed in a housing, electrolyte is injected, and the housing is sealed to obtain a battery monomer. One or more battery monomers are integrated to form a battery module, which can provide higher voltage and capacity, and has a specific function output; then one or more battery modules are installed in a battery box, and a battery management system and the like are usually added to form a battery pack, which is usually a product provided to users. Alternatively, one or more battery monomers can be directly installed in a battery box to form a battery pack.

[0135] Reference Figure 2 , which is an example of a battery module 4. In the battery module 4, a plurality of battery monomers 5 can be arranged in sequence along the length direction of the battery module 4. Of course, they can also be arranged in any other manner. Further, the plurality of battery monomers 5 can be fixed by fasteners.

[0136] Optionally, the battery module 4 can further comprise a housing having an accommodation space, and the plurality of battery monomers 5 are accommodated in the accommodation space.

[0137] Reference Figure 3 and Figure 4 , which is an example of a battery pack 1. The battery pack 1 can comprise a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box comprises an upper box 2 and a lower box 3, and the upper box 2 can be arranged on the lower box 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0138] In some embodiments, the battery can comprise an outer package. The outer package can be used to package the electrode assembly composed of the positive electrode sheet, the negative electrode sheet, and the separator, and the electrolyte.

[0139] The outer package of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc., or a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate, etc.

[0140] The shape of the battery can be cylindrical, square, or any other arbitrary shape. For example, Figure 5 is a battery with a square structure as an example.

[0141] In some embodiments, referring to Figure 6 , the outer package can include a shell 51 and a cover plate 53. The shell 51 can include a bottom plate and a side plate connected to the bottom plate, which enclose a receiving cavity. The shell 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 through a winding process or a stacking process. One or more electrode assemblies 52 are packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52.

[0142] The application also provides a power consuming device comprising the above battery.

[0143] The battery disclosed in the embodiments of the application can be used in a power consuming device using the battery as a power source, or various energy storage systems using the battery as an energy storage element, to provide electric energy. The power consuming device can include, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. The electric toy can include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric plane toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle, a spacecraft, etc. As the power consuming device, the battery cell, the battery module, or the battery pack in the battery can be selected according to the use requirements.

[0144] Figure 7 is a power consuming device as an example. The power consuming device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the power consuming device for the battery, a battery pack or a battery module can be used.

[0145] The specific embodiments will be described below.

[0146] Embodiment A1

[0147] The embodiment provides an electrode sheet processing system, referring to Figure 1 , the electrode sheet processing system comprises:

[0148] a conveying unit 20 for conveying the electrode sheet 10, the conveying unit 20 comprising an unwinding guide roller 21 and a winding guide roller 22;

[0149] a flame heating unit 30 including a spray gun burner (hereinafter referred to as a spray gun) for spraying a premixed combustion flame and performing a flame heating process on the pole piece 10, using natural gas (premixed with air) as a gaseous fuel. The spray gun includes a spray gun port through which the premixed natural gas-air mixture is burned to spray the premixed combustion flame. The spray gun port has a size of 2-3 cm in width and 5-20 cm in length, and the size of the spray gun port can be adjusted as needed. The premixed combustion flame sprayed from the spray gun port has a rectangular cross section corresponding to the shape of the spray gun port, and the size of the rectangular cross section corresponds to the size of the spray gun port. In the pole piece heating system in the present embodiment, two spray guns using the same combustion conditions are provided, and the two spray guns are located equidistantly on both sides of the surface of the pole piece 10, and the premixed combustion flames generated by the two spray guns are perpendicular to the surface of the pole piece 10.

[0150] The pole piece processing system of the present embodiment further includes a drying unit, a roller pressing unit, a cooling unit, and a temperature measuring unit (not shown in the drawing). Figure 1 The drying unit, the roller pressing unit, the flame heating unit 30, and the cooling unit are arranged in sequence in the conveying direction (direction D in the drawing) of the pole piece. Figure 1

[0151] The drying unit is used to perform a drying process on the pole piece coated with the electrode paste, the roller pressing unit performs roller pressing on the pole piece processed by the drying unit, the cooling unit performs cooling on the pole piece after the flame heating process, so as to facilitate the winding of the pole piece 10 by the winding guide roller 22. The temperature measuring unit measures the temperature of the pole piece 10 in the flame heating process.

[0152] In the present embodiment, the pole piece processing system further includes an automatic temperature control unit (not shown in the drawing), which is used to control the combustion conditions of the spray gun according to the temperature of the pole piece 10 measured by the temperature measuring unit. Figure 1

[0153] The working process of the pole piece processing system of the present embodiment includes:

[0154] After the electrode paste is coated on the current collector and is dried by the drying unit and is roller pressed by the roller pressing unit, the pole piece 10 with a dried active layer is formed. The pole piece 10 rapidly passes through the flame generated by the spray gun under the conveying of the conveying unit 20, so as to realize the flame heating process on the pole piece 10.

[0155] During the flame heating process, the temperature measuring unit monitors the temperature of the pole piece 10 in real time; at the same time, the automatic temperature control unit receives the temperature data of the pole piece 10 measured by the temperature measuring unit, and adjusts and controls the combustion conditions of the spray gun according to the data, so as to maintain the temperature of the pole piece 10 within the required temperature range. ​​

[0156] Example B1

[0157] This embodiment provides a method for processing positive electrode sheets, which involves processing the positive electrode sheets in the electrode processing system of Embodiment A1, specifically including the following steps:

[0158] 1) Preparation of positive electrode sheet

[0159] Nickel-cobalt-manganese (NCM) ternary material, conductive agent carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) were mixed evenly in a mass ratio of 96.9:2:1:21 to obtain a positive electrode slurry. The positive electrode slurry was then uniformly coated onto the positive electrode current collector aluminum foil, and then dried, cold-pressed, and slit to obtain the positive electrode sheet.

[0160] 2) Flame heating treatment of the positive electrode sheet

[0161] The obtained positive electrode sheet is used... Figure 1 The electrode processing system shown undergoes flame heating treatment. During the treatment, the premixed combustion flame generated by the spray gun comes into contact with the positive electrode. The air flow rate in the spray gun is 250 L / min, the natural gas flow rate is 6 L / min, the air-fuel ratio is 3, and the flame temperature is 600℃. The electrode conveyor speed is controlled at 100 m / min. The electrode temperature and carbon deposition on the electrode surface are recorded during the conveyor process.

[0162] Example B2

[0163] This embodiment provides a method for processing positive electrode sheets, which differs from Embodiment B1 only in that: step 2) controls the electrode sheet conveying speed to be 80 m / min. Everything else is the same as in Embodiment B1.

[0164] Example B3

[0165] This embodiment provides a method for processing positive electrode sheets, which differs from Embodiment B1 only in that: step 2) controls the electrode sheet conveying speed to be 60 m / min. Everything else is the same as in Embodiment B1.

[0166] Example B4

[0167] This embodiment provides a method for processing positive electrode sheets, which differs from Embodiment B1 only in that: step 2) controls the electrode sheet conveying speed to be 40 m / min. Everything else is the same as in Embodiment B1.

[0168] Comparative Example B1

[0169] This comparative example provides a method for processing a positive electrode sheet, which differs from Example B1 only in that the positive electrode sheet does not undergo the flame heating treatment in step 2).

[0170] Comparative Example B2

[0171] This comparative example provides a method for processing a positive electrode sheet, which differs from Example B1 only in that: step 2) controls the electrode sheet conveying speed to be 10 m / min. Everything else is the same as in Example B1.

[0172] In this comparative example, the electrode sheet was burned off during the processing.

[0173] Comparative Example B3

[0174] This comparative example provides a method for processing positive electrode sheets, differing from Example B1 only in that the spray gun is replaced with an alcohol lamp, the flame (outer flame) temperature of the alcohol lamp is 400°C, and the electrode sheet conveying speed is controlled at 10 m / min. Everything else is the same as in Example B1.

[0175] In this comparative example, the combustion of the alcohol lamp is diffusion combustion, and the resulting flame is clearly divided into a flame core, an inner flame, and an outer flame. Furthermore, considering the low flame temperature of the alcohol lamp, the electrode conveyor speed is controlled at a low speed of 10 m / min during the processing of the positive electrode to increase the contact time between the electrode and the flame, thereby raising the electrode temperature during the flame heating process.

[0176] Example C1

[0177] This embodiment provides a method for processing negative electrode sheets, which involves processing the negative electrode sheets in the electrode processing system of Embodiment A1, specifically including the following steps:

[0178] 1) Preparation of negative electrode sheet

[0179] The active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are dissolved in deionized water at a mass ratio of 96.2:0.8:0.8:1.2 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is uniformly coated onto the negative electrode current collector copper foil once or multiple times, and then dried, cold-pressed, and slit to obtain the negative electrode sheet.

[0180] 2) Flame heating treatment of negative electrode sheet

[0181] The obtained negative electrode sheet is used Figure 1 The processing system shown performs flame treatment. During the treatment, the premixed combustion flame generated by the spray gun comes into contact with the negative electrode sheet. The air flow rate in the spray gun is 180 L / min, the natural gas flow rate is 6 L / min, the air-fuel ratio is 4, and the flame temperature is 800℃. The electrode sheet conveying speed is controlled at 100 m / min, and the electrode sheet temperature and carbon deposition on the electrode sheet surface are recorded during the conveying process.

[0182] Example C2

[0183] The embodiment provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that the step 2) controls the running speed of the electrode sheet to be 80 m / min. The others are the same as the embodiment C1.

[0184] Embodiment C3

[0185] The embodiment provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that the step 2) controls the running speed of the electrode sheet to be 60 m / min. The others are the same as the embodiment C1.

[0186] Embodiment C4

[0187] The embodiment provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that the step 2) controls the running speed of the electrode sheet to be 40 m / min. The others are the same as the embodiment C1.

[0188] Comparative Example C1

[0189] The comparative example provides a method for processing a negative electrode sheet, which is different from the embodiment C1 only in that the negative electrode sheet does not undergo the flame heating treatment in the step 2).

[0190] Comparative Example C2

[0191] The comparative example provides a method for processing a positive electrode sheet, which is different from the embodiment C1 only in that the step 2) controls the running speed of the electrode sheet to be 10 m / min. The others are the same as the embodiment C1.

[0192] The comparative example shows that the electrode sheet is burnt out during the processing.

[0193] The electrode sheet processing conditions of the embodiments and the comparative examples are shown in Table 1, and the electrode sheet temperature (specifically, the active layer temperature) and the electrode sheet carbon deposition during the processing of the embodiments and the comparative examples are shown in Table 2. In Table 2, the “active layer surface temperature” is the active layer surface temperature (also the electrode sheet surface temperature) about 6 cm downstream of the flame heating. The active layer surface temperature about 6 cm downstream is selected for the convenience of temperature measurement, and the measured temperature is considered to be the same as the active layer surface temperature treated by the flame heating.

[0194] The electrode sheets after the processing of the embodiments and the comparative examples are tested for performance, including the electrolyte absorption rate, the porosity, the membrane resistance, the adhesion and the like, and the results are shown in Table 3.

[0195] Table 1. Electrode sheet processing conditions of the embodiments and the comparative examples

[0196]

[0197]

[0198] Table 2. Surface temperature of the pole piece and carbon deposition of the pole piece of each example and the comparative example

[0199]

[0200] Table 3. Test results of the pole piece performance

[0201]

[0202] The data in Table 3 were processed to obtain the change rate of each performance of the pole piece of each example and the comparative example after processing compared with the pole piece before processing, as shown in Table 4.

[0203] Table 4. Change rate of the pole piece performance of each example and the comparative example

[0204]

[0205]

[0206] In Table 4, the change rate of each item of Example B1 to Example B4 and Comparative Example B1 to Comparative Example B3 is the change rate compared with Comparative Example B1, and the change rate of each item of Example C1 to Example C4 and Comparative Example C1 to Comparative Example C2 is the change rate compared with Comparative Example C1.

[0207] For example:

[0208] The change rate of the liquid absorption rate of the pole piece of Example B1 = (the liquid absorption rate of the pole piece of Example B1 - the liquid absorption rate of the pole piece of Comparative Example B1) / the liquid absorption rate of the pole piece of Comparative Example B1 * 100%;

[0209] The change rate of the liquid absorption rate of the pole piece of Example B2 = (the liquid absorption rate of the pole piece of Example B2 - the liquid absorption rate of the pole piece of Comparative Example B1) / the liquid absorption rate of the pole piece of Comparative Example B1 * 100%;

[0210] The change rate of the liquid absorption rate of the pole piece of Example C1 = (the liquid absorption rate of the pole piece of Example C1 - the liquid absorption rate of the pole piece of Comparative Example C1) / the liquid absorption rate of the pole piece of Comparative Example C1 * 100%;

[0211] The change rate of the liquid absorption rate of the pole piece of Example C2 = (the liquid absorption rate of the pole piece of Example C2 - the liquid absorption rate of the pole piece of Comparative Example C1) / the liquid absorption rate of the pole piece of Comparative Example C1 * 100%.

[0212] The change rate of other items is calculated in the same way.

[0213] The test results show that:

[0214] The liquid absorption rate of the electrode sheet of Example B1 to Example B4 and Example C1 to Example C4 is obviously improved after flame heating treatment under suitable conditions. Among them, the liquid absorption rate of the positive electrode sheet in Example B1 to Example B4 is increased by more than 34% after flame heating treatment, and even up to 100%; the liquid absorption rate of the negative electrode sheet in Example C1 to Example C4 is also increased by more than 18% after flame heating treatment. The significant improvement of the liquid absorption rate reflects that the wettability of the electrolyte to the electrode sheet is greatly improved after the electrode sheet is treated by flame heating.

[0215] It can be found in combination with the change of the porosity of the electrode sheet that one of the reasons for the improvement of the liquid absorption rate of the electrode sheet is that the porosity of the electrode sheet is improved after the flame heating treatment. The improvement of the porosity is mainly due to the softening (melting) or ablation of the binder floated to the surface of the electrode sheet during the flame heating treatment, which exposes more capillaries of the electrode sheet and increases the channel for the electrolyte to infiltrate the electrode sheet. Moreover, in the flame combustion treatment, the premixed combustion flame generated by the spray gun does not form coke on the surface of the electrode sheet to block the pores (for example, the EDS test of the negative electrode sheet of Comparative Example C1 shows that the C content is 99.19wt%, and the O content is 0.81wt%; while the C content of the negative electrode sheet of Example C3 after flame heating treatment is 99.22wt%, and the O content is 0.78wt%, which is equivalent to that before the flame heating treatment), which is conducive to further improving the porosity of the electrode sheet. Therefore, by treating the electrode sheet by suitable flame heating treatment, the porosity of the electrode sheet can be effectively improved, and the wettability of the electrolyte to the electrode sheet can be improved.

[0216] At the same time, corresponding to the porosity of the electrode sheet, within a certain range, the sheet resistance of the electrode sheet gradually decreases with the increase of the porosity of the electrode sheet. For example, the sheet resistance of the positive electrode sheet in Example B1 to Example B4 is reduced by more than 16% after flame heating treatment, and the highest can be close to 30%; the sheet resistance of the negative electrode sheet in Example C1 to Example C4 is reduced by more than 8% after flame heating treatment, and the highest can be close to 15%. The sheet resistance of the electrode sheet is affected by the surface morphology of the electrode sheet. After the electrode sheet is treated by flame heating under certain conditions, the surface morphology changes, such as the improvement of the porosity, which can not only improve the wettability of the electrolyte to the electrode sheet, but also greatly reduce the sheet resistance of the electrode sheet and improve the electrochemical performance of the electrode sheet.

[0217] In addition, the test results show that the electrode sheet still has good adhesion after flame heating treatment under suitable conditions.

[0218] In contrast, when the pole piece is subjected to flame heating treatment under inappropriate conditions, for example, after the flame heating treatment of Comparative Example B2 and Comparative Example C2, the surface temperature of the pole piece is too high (higher than the lowest temperature among the decomposition temperature, the oxidation temperature, and the ignition temperature of the active material in the pole piece), resulting in the pole piece being damaged by burning out. For another example, after the flame heating treatment of Comparative Example B3, the surface temperature of the pole piece is too low (lower than the softening or melting temperature of the active material in the binder), the liquid absorption rate of the pole piece changes little compared with that before the flame heating treatment; at the same time, the porosity of the pole piece decreases and the sheet resistance of the pole piece increases compared with those of the pole piece without the flame heating treatment.

[0219] In summary, during the flame heating treatment of the pole piece, controlling the temperature of the pole piece within a certain range can effectively improve the porosity of the pole piece, thereby improving the wettability of the electrolyte to the pole piece and being conducive to improving the sheet resistance of the pole piece.

[0220] Appendix: The above-mentioned related performance test methods are as follows:

[0221] (1) Liquid absorption rate of electrolyte of pole piece

[0222] The pole piece was fixed on a clean glass plate, and 3 mm of electrolyte (the electrolyte composition included EC, DMC and EMC in a volume ratio of 3:2:1, and 1 mol / L of lithium salt LiPF6) was sucked by a 0.2 mm (inner diameter) capillary tube, then the pole piece was vertically contacted with the electrolyte to absorb the electrolyte, and the time for absorbing the electrolyte was measured to obtain the electrolyte absorption rate by conversion.

[0223] (2) Porosity of pole piece

[0224] In a dry room, >20 round pole pieces with good appearance and no powder on the edge were selected and loaded into a sample cup with tweezers. The number of pieces was recorded, and the apparent volume of all the pole pieces was calculated. The sample cup loaded with the sample was placed in a true density tester, and the system was closed. Helium was introduced according to the program, and the pressures of the gas in the sample chamber and the expansion chamber were detected. Then, according to the Boyle's law (PV=nRT), the true volume of all the pole pieces was calculated to obtain the porosity of the sample [porosity=(V0-V) / V*100%, wherein V0 is the apparent volume of the pole piece, and V is the true volume of the pole piece].

[0225] (3) Sheet resistance

[0226] The sheet resistance was tested by using the sheet resistance tester of Yuan Neng Technology. Small round pieces with a diameter of 10 mm were cut from the left, middle and right of the pole piece. The indicator light of the sheet resistance tester of Yuan Neng Technology was turned on, and the "probe" was placed in the appropriate position. Then, the "start" button was clicked, and the reading was obtained after the reading was stable. Two positions of each small round piece were tested, and the average value of six measurements was calculated as the sheet resistance of the pole piece.

[0227] (4) Adhesion

[0228] Cut the electrode sheet to 20*100mm 2 The test sample of the required size is prepared; the sample is bonded with double-sided tape on the side to be tested, and is compacted with a roller to ensure that the double-sided tape is fully bonded to the sample; the other side of the double-sided tape of the sample is bonded to a stainless steel surface, and one end of the sample is bent in the opposite direction at an angle of 180°; a high-tension testing machine is used to test, with one end of the stainless steel fixed to the lower clamp of the testing machine and the bent end of the sample fixed to the upper clamp; the angle of the sample is adjusted to ensure that the upper and lower ends are perpendicular, and then the sample is stretched at a speed of 50 mm / min until the sample is completely peeled off the substrate; the displacement and force during the process are recorded, and the force at which the sample is considered to be in equilibrium is taken as the adhesion of the electrode sheet.

[0229] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A pole piece processing system characterized by, The application relates to a battery pole piece processing system and a battery pole piece processing method. The battery pole piece processing system comprises a flame heating unit for flame heating treatment on opposite sides of a pole piece surface; the pole piece comprises an active layer comprising an active substance and a binder, and the flame heating treatment makes the surface layer temperature of the active layer greater than or equal to the softening temperature or melting temperature of the binder and less than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active substance. The flame heating unit comprises a flameless gas burner. In the flame heating treatment, the pole piece moves relative to the flame generated by the flame heating unit, and the moving speed of the pole piece relative to the flame is 40-100 m / min.

2. The pole piece processing system of claim 1, wherein The pole piece processing system further comprises a conveying unit for conveying the pole piece.

3. A method of processing a pole piece, characterized by, The pole piece comprises an active layer comprising an active substance and a binder; the method for processing the pole piece comprises: flame heating treatment on opposite sides of the pole piece surface, so that the surface layer temperature of the active layer is greater than or equal to the softening temperature or melting temperature of the binder and less than the lowest temperature among the decomposition temperature, oxidation temperature and ignition temperature of the active substance. The flame used in the flame heating treatment comprises premixed combustion flame generated by a flameless gas burner. In the flame heating treatment step, the pole piece moves relative to the flame, and the moving speed of the pole piece relative to the flame is 40-100 m / min.

4. The method of claim 3, wherein the polar plate is processed by, The temperature of the premixed combustion flame is 500-1200 DEG C.

5. The method of claim 4, wherein the polar plate is processed by, The temperature of the premixed combustion flame is 600-1000 DEG C.

6. The method of treating a pole piece according to any one of claims 3-5, wherein, The flameless gas burner comprises any one or more of the following technical parameters: (1) air flow is 50-250 L / min; (2) gas fuel flow is 2-15 L / min; (3) air-fuel ratio is 1-7.

7. The method of claim 6 wherein the pole piece is processed by, The flameless gas burner comprises any one or more of the following technical parameters: (1) air flow is 80-150 L / min; (2) gas fuel flow is 5-10 L / min; (3) air-fuel ratio is 3-5.

8. The method of claim 3, wherein the polar plate is processed by, The moving speed of the pole piece relative to the flame is 60-80 m / min.

9. The method of treating a pole piece according to any one of claims 3-5, wherein, The surface layer temperature of the active layer is 180-500 DEG C.

10. The method of claim 9, wherein the polar plate is processed by, The surface layer temperature of the active layer is 300-500 DEG C.

11. A pole piece characterized by, The porosity of the pole piece is 30%-50%; The pole piece is processed according to the method in any one of claims 3-10.

12. The pole piece of claim 11, wherein The porosity of the pole piece is 30%-47%.

13. A battery, characterized by The battery comprises the pole piece in claim 11 or 12.

14. An electrical device, comprising: The electric device comprises the battery in claim 13.

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